Reinforced bonded abrasive cup wheel

ABSTRACT

Bonded abrasive flaring cup wheels, e.g., &#39;&#39;&#39;&#39;Type 11&#39;&#39;&#39;&#39; grinding wheels, are reinforced in the rim portion of the wheel with a substantially flat annular reinforcing strip, typically formed of open mesh woven glass fiber. The annular reinforcing strips are typically formed to a diameter greater than that which will ultimately be required in the grinding wheel and cut at one location in order to allow placement over the diverging frustoconical male mold member used to produce the flaring cup configuration. The ends of the glass fiber reinforcing strip are then overlapped within the mold as the resin coated abrasive grain is being added within the mold cavity. The result is a reinforced bonded abrasive cup wheel having substantially greater strength after having been damaged than the prior art bonded abrasive cup wheel.

United States Patent Rim [451 July 29, 1975 REINFORCED BONDED ABRASIVE CUP WHEEL Primary ExaminerAl Lawrence Smith Assistant Examiner-K. J. Ramse [75] inventor: James C. Rme, North Tonawanda, Attorney, Agent or Firm David Dougherty;

Raymond W. Green [73] Assignee: The Carborundum Company,

Niagara Falls, NY. [57] ABSTRACT [22] Filed: 1974 Bonded abrasive flaring cup wheels, e.g., Type II 2 Applg 453 9 9 grinding wheels, are reinforced in the rim portion of the wheel with a substantially flat annular reinforcing strip, typically formed of open mesh woven glass fiber. [52] US. Cl 51/209 R; 51/206 NF The annular reinforcing strips are typically formed to [5 o a a i I I a e I a [58] Field of Search 51/206 NF, 209 R; required in the grinding wheel and cut at one location 161/1316 4 in order to allow placement over the diverging frustoconical male mold member used to produce the flar- [56] References C'ted ing cup configuration. The ends of the glass fiber rein- UNITED STATES PATENTS forcing strip are then overlapped within the mold as 2949,698 8/1960 Downey et a1 i6l/DIG. 4 the resin coated abrasive grain is being added within 3,l4l,27l 7/1964 Fischer et al. 5I/206 NF the mold cavity. The result is a reinforced bonded 3,431,687 3/1969 Fischer et al. 5l/206 NF abrasive cup whee] having ubstantially greater 3540,l63 l1/1970 Shoemaker a 51/209 R strength after having been damaged than the prior art 3,746,266 7/1973 Knox et al. 51/206 NF bonded abrasive Cup wheel FOREIGN PATENTS OR APPLICATIONS 12 Claims 3 Drawing Figures 580,394 8/l958 ltaly 5l/206 NF PAYENTED JUL 2 9 I975 SHEET PATENTED JUL 2 9 I975 FIG. 3

7 i REKNFORCEDBONDED ABRASKVE CUP WHEEL BACKGROUND OF THE INVENTION This invention relates to reinforced bonded abrasive cup wheel. More particularly, this invention relates to reinforced bonded abrasive grinding wheels havinga back portion and an annular diverging rim portion, the diverging rim portion being integrally formed withthe back portion; the diverging rim portion having a diverging frusto-conical inner surface, the smaller diameter of the diverging frusto conical inner surface being adjacent the back portion of the grinding wheel. This type of wheel is known in the industry as a flaring cup wheel, and a typical configuration has been given the designation Type ll wheel in the United States by the Grinding Wheel Institute. See American National Standard Safety Code For The Use, Care And Protection Of Abrasive Wheels, published 1970 by the American National Standard institute, lnc., the disclosure of which is incorporated by reference. The Type 1 1 wheel is to be distinguished from the Type 6 straight cup wheel, wherein the rim portion is a non-diverging annulus.

Flaring cup wheels are usually formed in an upright position, with the female mold member, which has the size and shape desired for the outer surface of the annular diverging rim portion of the wheel and for the face of the back portion adjoining the outer surface of the annular diverging rim portion of the wheel, being positioned under and around the wheel which is to be formed. This is done for manufacturing convenience, for example the ability to place within the female mold member, prior to the placement of any bonding material or abrasive grain, a backing plate. This results in the male mold member, which has the size and shape desired for the inner surface of the annular diverging surface of the annular diverging rim portion of the bonded abrasive grinding wheel and for the face of the back portion adjoining the inner surface of the annular diverging rim portion of the wheel, being placed over' the initial quantity of abrasive grain and bonding material, prior to building up the annular rim portion of the wheel. The use of substantially flat annular reinforcing strips or discs such as open mesh woven glass fiber, containing openings of the size between about 2 and about 3 millimeters between the woven filaments of the woven glass fiber, as reinforcements for other types of grinding wheels is conventional. Such reinforcements could be used in the flaring cup wheel without restric- LII maximum outer diameter of the male mold member which is used to form the rim of the flaring cup wheel.

SUMMARY OF THE lNVEhITlON it is, therefore, an object of the invention to provide a bonded abrasive grinding wheel having a back portion and an annular diverging rim portion, the diverging rim portion being integrally formed with the back portion, the diverging rim portion having a diverging frusto-conical inner surface, the smaller diameter of the di verging frusto-conical inner surface being adjacent the back portion of the'grinding wheelywherein the improvement comprises the provision of at least one subaccordance with the present invention, by (l) placing a quantity of abrasive grain coated with uncured resin in a female mold member, the female mold member I having the size and shape desired for the outer surface of the annular diverging rim portion of the bonded abrasive grinding wheel and for the face of the back portion'of the grinding wheel adjoining the outer surface of the annular diverging rim portion of the grinding wheel, the'quant'ity of resin coated abrasive grain being sufficient to fill the female mold member to the level corresponding to the smaller diameter of the di verging frusto-conical inner surface of the diverging rim portion of the bonded abrasive grinding wheel; (2) placing within the female mold member a male mold member, over the quantity of resin coated abrasive grain within the female mold member, the male mold tion, only prior to the placement of the male mold member within the female mold member. Thus, the

back portion of the flaring cup wheel can contain as flat annular reinforcing strips will not fit over the male mold member, unless the inner diameter is at least as large as the maximum (upper) diameter of the male mold member. The result is that if reinforcing strips were to be used at all in the, rim portion of a flaring cup wheel, theinner diameter of the reinforcing strips would heretofore have had to be at least as large as the member having the size and shape desired for the inner surface of the annular diverging surface of the annular diverging rim portion of the grinding wheel and for the face of the back portion of the grinding wheel adjoining the inner surface of the annular diverging rim portion of thebonded abrasive grinding wheel, for forming a cavity corresponding to the annular diverging rim portion between the female mold member and the male mold member; (3) placing additional abrasive grain coated with uncured resin in the cavity between the female mold member and the male mold member, while (4) periodically inserting within the cavity between the female mold member and the male mold member, the substantially flat annular reinforcing strips, the annular reinforcing strips having, after placement, an inner diameter less than the maximum diameter of the diverging frusto-conical inner surface of the diverging rim portion of the grinding wheel, and being placed substantially perpendicular to the axis of the male mold member; and (5) compressing and curing the resin coating of the abrasive grain, for forming an integrally bonded abrasive grinding wheel.

BRlEF DESCRlPTlON OF THE DRAWINGS H6. 1 is a vertical sectional view of a reinforced bonded abrasive grinding wheel in accordance with the present invention.

HQ. 2 is a broken away section of the wheel illustrated in HS. ll, taken alongline 2-43 of PEG. ii.

FIG. 3 illustrates the orientation of the grinding wheel with respect to the male and female mold members during the production of the grinding wheel.

DETAILED DISCLOSURE Referring now to FIG. 1, there'is illustrated a vertical cross-section of a reinforced bonded abrasive grinding wheel in accordance with the present invention; The

wheel comprises a back portion ll'andflan annular di verging rimportion 12, the diverging rim portion 12 being integrally formed with the back portion 11. The

the more common situation, however, it will be preferred to build up'the grinding wheel with the female,

' mold member underneath the grinding wheeLa single diverging rim portion 12 has adiverging frustoconical V inner surface 13, the smaller diameterlA'of the diverging frusto-conica! inner surface '13 being adjacent th.e;, V

back portion 11. The improvement in a'ccordance with the present, invention comprises the provision of at least one, and preferablyaplurality,of'substantiallyflats annular reinforcing strips 15-17 within the diverging rim :portion 12 of, the grindingwheel. The phrase fsub stantially flat annular reinforcingstrip as'used herein is genericto both an endlessstrip a; disc, having been 7 outwith only an inner circumference and anouter c'ir- V cumference, and a slitstrip or disc, i.e.,- an annular; reinforcin g strip which has been providedwitha pair ofren'd r portions, for example by cutting an endless annular re- V inforcing' strip; If asplu'ralityof annular reinforcing" strips 'l5 -s17 isused, they are preferably substantially equally'axially spaced throughout the annular rim portion 12 of the grinding wheel, If desired, there maybe VV provided one or more additional annular reinforcing strips 18 between the' back portion 11 andjtherim porpiece male mold member being used. This may be de sirable, for example, if a backing plateiis placed within:

the grinding wheelqwithin the femalemold member, prior to placingany resin coated abrasive grain in the V female moldtnember. In such a case, theannula r rein- I forcing strip or stripszare prOvidAedwitha pair of end? portions 25 and 2 6 (see RG 2); suitably by putting an] I "oversize anriular reinforcingistrip (for example, along the fradius of the annularreinforcing strip). By fever; 3 i s isefit is meant thattheannularstrips wiilhavegreater inner and outer diameterstprioli to cutting, thanthat of I the annular rim erson- 12 oftheigrinding' wheelciThe a pend portions of each annular reinforcing strip arefthen disposed within theanntrlar diverging rim portion i2 V the grindingfwheelin overlappingrelationship, as illus's trated in FIG. 2, wherein the numeral 27 designates the overlappingsection. of endportions 2 57 and 26. It iscp'referred'that theioverlapp'ed end portions of the annularff reinforcing strip or stripsare overlapped an amountequal-in distance to at leastaboutone width of the anmm 12, or lstwithin the back portion 11 of the grind-.

ing wheel. The annular reinforcing strip or strips l5-l9 are substantially perpendicular to theaxis 21 of the frusto-conical inner surface 13 of the diverging rim portion 12 of the grinding whejelQThe inner diameters of the annular reinforcing stripsfl 5-l7 within the annular diverging rirn' portion 12 of the grinding wheel are less'than the maximum diameter '22 of the diverging frusto-conical i nner surface l3 of the 'diverging rirn inventiomthe annular reinforcing strips 15519, are provided with indentations for engagementwith binder material of the grinding wheel. The annular reinforcing ings) for penetration with binder materialof the grind- 7 ing wheel, as this provides greater reinforcement Itis' further preferred, moreover, that the {annular reinforce ing strip or strips be woven filamentary material, in particular woven filamentary material V having; interstices formed thereim theinterstices being openings between r V the woven filaments of the woven filamentarylmatjerial, V

the openings ranging in size between about 2 and about 5 mold rnember as the annular; diverging rim portion 12;}; a of the grinding wheel is; being built'up, Inother'cases it willbe feasibleto utilizese'gmented male mold'merngnular reinforcingstrip; As used herein, thewidth" of V I the annular reinforcing strip is the difference between I aradius of the outsidediameter and a radius of the, in- I sidediameterof the annular reinforcing sftrip n In addlition to providingfa plurality of annularxreinforcing strips substantially equallyiaxially spaced I V t hroughoutthe annular rim portion of the grinding V V wheeLit is preferred;that the annular reinforcing strips V 7 belspaced at axial intervals at le ast as' close as one-half? inch betweenlthe. annular reinforcing strips; P V

i The preferred processi for producingabonded abra-i V sive grindingwheel in accordance withthepresentiinvention will nowbe describeiwith referenceto FIG,

V3; Ifdesired, abaekingplate 23 is first placedwithinthe VV a female mold member; Thefbacking plate23' may be: providedwith'protruding porti'ons'Mlforiengagementi t within the back p rti n 11 pr the grinding wheel, and; t xalso withthreadedportioniiil for engagement witha grinding machine for useofthewhe'el; a

, ing wheeladjoifningthe outer surfaCefBZ of theann ular t i diverging [rim portion "1210f the: grinding wheeln'lhe quantity of resincoated abrasive grain provided at this V V 7 point: is sufticientto f ll the female mold membertoth ef;

' levelgcorresponding to'vthe smaller diameter 1410s the V diverging frusto-conical innersurface 1130f the diverge: t

' ing ,rini-portion llof thezbohdedabtasive grinding {At this point; it isfpreferred to place one additionally" i annular reinforcing stripj; lg iwithin female jmoldf' {j member 39; overthe quantity of, resin coated abrasives t i gra'in filling the'fern'ale mold' memberj zil*tolthe level 7 corresponding to the smal lerdiameterld ofthe diyerg Next, or firs't if no'backihgplateis tobeused; aquan5 i, I 1

tityj of abrasive? grain coated, with uncured fresinis V placedVin the female mold member), the female'mold V s member-29 having the size-- and shape desired forthe 1 V outerlsufffi 32 of annular diverging rimportion'12} t V and'fo'r the face 33 .ofthefback portionll ofthefgrind ing frusto-conical inner surface 13 of diverging rim portion 12 of the grinding wheel.

Next there is placed within the female mold member 29 a male mold member 35, over the quantity of resin coated abrasive grain within the female mold member 29. The male mold member has the size and shape desired for the inner surface 13 of the diverging rim portion 12 of the grinding wheel, and of the face 36 of the back portion 11 of the grinding wheel adjoining the inner surface 13 of the annular diverging rim portion 12 of the grinding wheel. There is thus formed a cavity corresponding to the annular diverging rim portion 12 of the grinding wheel, between the female mold member 29 and the male mold member 35.1

Additional abrasive grain coated with uncured resin is then placed in the cavity between the female mold member 29 and the male mold member 35, while periodically inserting, within the cavity between the female mold member 29 and the male mold member 35, the substantially flat annular reinforcing strips 15-17, the annular reinforcing strips 15l7 having, after placement, an inner diameter less than the maximum diameter 22 of the diverging frusto-conical inner surface 13 of the diverging rim portion 12 of the grinding wheel. The annular reinforcing strips are also placed substantially perpendicular to the axis 21 of the male mold member which is, of course, the same as the axis 21 of the frusto-conical inner surface 13 of the diverging rim portion 12 of the grinding wheel after the grinding wheel is completed.

The resin coating of the abrasive grainis then compressed and removed from the mold, and cured in a conventional manner such as by placing the grinding wheel into a kiln. Any conventional resin can be used, however, phenolic resins (i.e., phenol-aldehyde resins) are usually preferred.

It is also preferred that the annular reinforcing strips include end portions, the end portions being disposed in overlapping relationship, as illustrated in FIG. 2.

If desired, at least one additional annular reinforcing strip 19 can be placed within the female mold member 29 within the resin coated abrasive grain filling the female mold member 29 to the level corresponding to the smaller diameter 34 of the diverging frusto-conical inner surface 13 of the diverging rim portion 12 of the grinding wheel. Such additional annular reinforcing strips will usually not be necessary however, if the,

backing plate 23 including protruding portions 30 is utilized.

The invention will now be illustrated with an example.

EXAMPLE A series of Type 1 l bonded abrasive grinding wheels having the cross-section illustratedin FIG. 1 were produced with zero, three or four annular reinforcing strips 15-18. The larger outer diameter (dimension D" as identified at page 10 of the abovepublication phenolic resin bonded aluminum oxide grain. The only differences between the wheels were the number and locations of annular reinforcing strips 15-18 provided in the wheels. In all cases, the reinforcing strips were woven glass fiber having a basket weave, the larger openings betweenthe woven filaments ranging in size between about 2 and about 3 millimeters, square. In all cases, for reinforced wheels one glass fiber reinforcing strip 18 was placed between the back portion 11 and the annular rim portion 12 of the grinding wheel. For those wheels containing four reinforcing strips, second, third and fourth strips were placed at substantially equally axially spaced intervals throughout the annularv rim portion of the grinding wheel, at axial intervals slightly less than /2-inch between the annular reinforcing strips. The grinding wheels containing three annular reinforcing strips had various configurations for the second and third strips.

Various discs produced as indicated above were subjected to speed tests, in which the grinding wheels were tested for ultimate speed in surface feet/minute attainable prior to fracture. The grinding wheels in some cases were subjected to impact loads ranging up to 74 ft. pounds, in various locations relative to the grinding wheel. The results of these tests are set forth in Table 1. In Table 1, under the heading TYPE OF IMPACT,

the letter A indicates a l-inch line impact parallel to the axis of the grinding wheel, on the grinding face (the 1% inch wide annular face of the diverging annular rim portion 12 of the grinding wheel). The letter B indicates an impact perpendicular to the axis of the grind-.

' TABLE 1 NUMBER OF IMPACT TYPE OF REINFORCING ULTIMATE (FOOT-POUNDS) IMPACT STRIPS SPEED (SFPM) NONE, 0 19,800

34 A 0 9,500 NONE 3 18,500 24 A 3 14.700

74 A 3 l2.l00 NONE 4 18.000

44 A I 4 15,400 54 A 4 14,600

74 A 4 14,800 3X54(l) A i 4 14,700 3 X 54 (2) A 4 15,000 3X74(1) A 4 l4,800 54 B 4 16,900

7 (1) Three impacts in same location.

(2) Three impacts in different locations.

In Table 1, each ultimate speed shown is the average of three trials, of identical wheels which had been subjectedto identical impact testing.

From the above, it can bev concluded that the inclusion of substantially flat annular reinforcing strips within the diverging rim portion of the grinding wheel 

1. A bonded abrasive grinding wheel having a back portion and an annular diverging rim portion, the diverging rim portion being integrally formed with the back portion; the diverging rim portion having a diverging frusto-conical inner surface, the smaller diameter of the diverging frusto-conical inner surface being adjacent the back portion of the grinding wheel; wherein the improvement comprises the provision of at least one substantially flat annular reinforcing strip of woven filamentary material having therein interstices for penetration with binder material of the grinding wheel, within the diverging rim portion of the grinding wheel, the annular reinforcing strip being substantially perpendicular to the axis of the frusto-conical inner surface of the diverging rim portion, and the inner diameter of the annular-reinforcing strip being less than the maximum diameter of the diverging frusto-conical inner surface of the diverging rim portion of the grinding wheel; wherein the annular reinforcing strip includes a pair of end portions, the end portions being disposed in overlapping relationship.
 2. A bonded abrasive grinding wheel according to claim 1, the openings ranging in size between about 2 and about 3 millimeters.
 2. placing within the female mold member a male mold member, over the quantity of resin coated abrasive grain within the female mold member, the male mold member having the size and shape desired for the inner surface of the annular diverging surface of the annular diverging rim portion of the bonded abrasive grinding wheel and for the face of the back portion of the grinding wheel adjoining the inner surface of the annular diverging rim portion of the bonded abrasive grinding wheel, for forming a cavity corresponding to the annular diverging rim portion between the female mold member and the male mold member;
 3. placing additional abrasive grain coated with uncured resin in the cavity bewteen the female mold member and the male mold member, while
 3. A bonded abrasive grinding wheel according to claim 2, wherein the woven filamentary material is glass fiber.
 4. A bonded abrasive grinding wheel acCording to claim 1, wherein the overlapped end portions of the annular reinforcing strip are overlapped an amount equal in distance to at least about one width of the annular reinforcing strip.
 4. periodically inserting, with the cavity between the female mold member and the male mold member, the substantially flat annular reinforcing strips, the annular reinforcing strips having, after placement, an inner diameter less than the maximum diameter of the diverging frusto-conical inner surface of the diverging rim portion of the grinding wheel, and being placed substantially perpendicular to the axis of the male mold member; wherein the annular reinforcing strips include end portions, the end portions being disposed in overlapping relationship; and
 5. compressing and curing the resin coating of the abrasive grain, for forming an integrally bonded abrasive grinding wheel.
 5. A bonded abrasive grinding wheel according to claim 1, comprising a plurality of annular reinforcing strips within the diverging rim portion of the grinding wheel.
 6. A bonded abrasive grinding wheel according to claim 5, wherein the plurality of annular reinforcing strips are substantially equally axially spaced throughout the annular rim portion of the grinding wheel.
 7. A bonded abrasive grinding wheel according to claim 5, wherein the annular reinforcing strips are each woven glass fiber, the strips being provided with openings of a size between about 2 and about 3 millimeters between the woven filaments of the woven glass fiber, and having ends overlapped an equal amount equal to at least about one width of the annular reinforcing strip.
 8. A bonded abrasive grinding wheel according to claim 7, wherein the annular reinforcing strips are spaced at axial intervals at least as close as one-half inch between the annular reinforcing strips.
 9. A process for producing a bonded abrasive grinding wheel according to claim 1, comprising the steps of
 10. A process according to claim 9, comprising in addition placing within the female mold member an additional substantially flat annular reinforcing strip, over the quantity of resin coated abrasive grain filling the female mold member to the level corresponding to the smaller diameter of the diverging frusto-conical inner surface of the diverging rim portion of the grinding wheel, prior to placement of the male mold member within the female mold member.
 11. A process according to claim 9, comprising in addition placing at least one additional annular reinforcing strip within the female mold meMber within the resin coated abrasive grain filling the female mold member to the level corresponding to the smaller diameter of the diverging frusto-conical inner surface of the diverging rim portion of the bonded abrasive grinding wheel.
 12. A process according to claim 9, comprising in addition placing a backing plate within the female mold member, prior to placing any resin coated abrasive grain in the female mold member. 